That should be doable. Are there any circuits you can make that produce shapes or other things?
I don't have a signal generator.
I assume you mean Tek 2465 oscilloscope. If you've got a front end (tuner, demodulator) that gives you composite video, you can make a converter that takes the NTSC (or PAL) composite video and creates the X, Y and Z voltages to drive the scope - turning the scope into a crude video monitor - like this:
And, here are a few videos showing XY graphics on an oscilloscope: